Embodiments of this disclosure relate generally to laser sources, and more particularly, to an apparatus that converts tunable narrow-linewidth lasers that are low power and continuous wave into tunable high power pulsed laser required for nonlinear frequency conversion.
Spectroscopy is the study of the interaction between radiation (electromagnetic radiation, or light, as well as particle radiation) and matter. Spectroscopy is often used in physical and analytical chemistry for the identification of substances through the spectrum emitted from or absorbed by them.
In a Laser Induced Breakdown Spectroscopy (LIBS), a highly energetic laser pulse is used as an excitation source. LIBS can analyze any matter regardless of the state of the matter. Since all elements emit light when excited to sufficiently high temperatures, LIBS can detect all elements, limited only by the power of the laser as well as the sensitivity and wavelength range of the spectrograph & detector.
Recently, LIBS has been used to help identify hazardous compounds. However, for certain hazardous compounds, the spectroscopic signatures lie in spectral regions that do not correspond to existing laser sources. As a result nonlinear optical wavelength conversion is often employed to generate such laser sources. Such techniques, in particular the use of Optical Parametric Oscillators, produce a laser output that is spectrally broad and unsuited for highly selective spectral detection. While line narrowing techniques exist they typically impede the tuning of the laser.
Laser spectroscopic detection of hazardous substances requires a laser source that is not only tunable throughout the region of spectral interest, but also possessing a very narrow frequency linewidth within that spectral region. Laser sources available in the spectral regions corresponding to the spectroscopic signatures of most hazardous materials are limited in tunability or suffer from excessive linewidth. While tunable narrow-linewidth lasers that are low power and continuous wave are available, such tunable narrow-linewidth devices are not readily available in a high powered pulsed format.
Therefore, it would be desirable to provide an apparatus that overcomes the above problems. The apparatus would be able to generate a broadly tunable laser beam which would maintain a narrow linewidth throughout its tuning range.